Multiphase PVC/styrenic copolymer alloys: Internally reinforced by partial miscibility

Although polymer/polymer miscibility is considered the exception to the general rule, in polymer thermodynamics specific interactions between active sites on two polymers can be a driving force for polymer/polymer miscibility. Both the intermolecular interactions of the alpha hydrogen of PVC with carbonyl groups in various polyesters and the polarity of the chlorine bond have been claimed to promote miscibility. Both of these interactions are potential in PVC/styrene maleic anhydride (SMAnh) polymer blends. These specific interactions promoting miscibility and the resulting mechanical properties of these systems is the subject of this report. SMAnh (12.5% MA) copolymer was melt compounded with a stabilized PVC compound using a Haake Rheocord twin screw extruder. Test data generated for these blends were analyzed for miscibility and effects of SMAnh copolymers on heat resistance, fire retardance, impact strength, and processability of PVC.     

Miscibility and rheological properties of poly(vinyl chloride)/styrene–acrylonitrile blends prepared by melt extrusion

Styrene–acrylonitrile (SAN) with acrylonitrile (AN) concentrations of 11.6–26 wt % and α‐methylstyrene acrylonitrile (αMSAN) with a wide range of AN concentrations are miscible with poly(vinyl chloride) (PVC) through solution blending. Here we examine the rheological properties and miscibility of PVC/SAN and PVC/αMSAN blends prepared by melt extrusion for commercial applications. We have investigated the rheological properties of the blends with a rheometer and a melt indexer. The PVC/SAN and PVC/αMSAN blends have a low melting torque, a long degradation time, and a high melt index, and this means that they have better processability than pure PVC. The miscibility of the blends has been characterized with differential scanning calorimetry, dynamic mechanical thermal analysis, and advanced rheometrics expansion system analysis. The miscibility of the blends has also been characterized with scanning electron microscopy. The SAN series with AN concentrations of 24–31 wt % is immiscible with PVC by melt extrusion, whereas αMSAN with 31 wt % AN is miscible with PVC, even when they are blended by melt extrusion, because of the strong interaction between PVC and αMSAN. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Aspects of miscibility in poly(vinyl chloride)/epoxidized natural rubber blends. Part II: Dynamic mechanical properties

Miscibility in poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends was further investigated by means of dynamic mechanical analysis. The single glass transition temperature shown by the blends supported earlier observations of miscibility Furthermore, observed synergism in storage modulus has again reaffirmed the miscibility of these blends. A critical examination of the damping peaks at various compositions again revealed the microheterogeneous nature of the blends. Some theories relating glass transition temperature and modulus with miscibility were also used to examine miscibility. Agreement of the results with theories proposed by Gordon—Taylor and Kleiner has provided a further insight into the miscible nature of PVC/ENR blends.     

Aspects of miscibility in poly(vinyl chloride)/epoxidized natural rubber blends. Part I: Mechanical and morphological properties

Miscibility in poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends was studied by examining evidence from tensile, impact, and physical properties. The observation of synergism in tensile strength, percent elongation at break, hardness, and relative density has reaffirmed PVC/ENR blends as miscible systems. Studies of impact properties, however, revealed that the blends are microheterogeneous in nature. This could be attributed to the large sizes of polymer molecules involved and the microgel content of ENR-50. Results from Fourier transform infrared spectroscopy (FTIR) revealed that hydrogen bonding is extensively involved in PVC/ENR systems. This evidence unveiled the exact nature of the specific interactions responsible for miscibility and hence the enhanced mechanical properties of PVC/ENR blends.     

Mechanical and thermal properties of poly(vinyl chloride)/α‐methyl‐styrene‐acrylonitrile blends prepared by melt extrusion

In this article, we have examined the physical and mechanical properties of poly(vinyl chloride) (PVC)/α‐methyl‐styrene‐acrylonitrile (αMSAN; 31 wt % AN concentrations) blends with different blend ratios. And, we also examined the effect of the molecular weights of PVC on the miscibility and material properties of the blends prepared by melt extrusion blending. Our results showed that the PVC/αMSAN blends have good processing properties and good miscibility over all blend ratios because of the strong interaction between PVC and αMSAN. And, the blends showed enhanced mechanical and thermal properties. In addition, high molecular weight PVC showed reasonable processability when melt blended with αMSAN, which resulted in enhanced mechanical and physical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Evaluation of the effects of acetyl tributyl citrate as bio‐based plasticizer on the physical,thermal, and dynamical mechanical properties of poly(vinyl chloride)/polymethyl methacrylate blends

This article details our work in studying the plasticization of Poly(vinyl chloride) (PVC)/Polymethyl methacrylate (PMMA) blends with bio‐based acetyl tributyl citrate (ATBC) in place of conventional plasticizers such as di(2‐ethylhexyl) phthalate. PMMA was blended with PVC in various ratios from 0 to 100 wt% by melt compounding with or without the plasticizer ATBC. Both the glass transition temperatures of the blends (differential scanning calorimetry) and Tα (dynamic mechanical thermal analysis) are consistent with a miscibility of the components, and Fourier transforms infrared spectroscopy studies show that there are specific interactions in the PVC/PMMA blends favoring the miscibility. The thermal degradation of the blends was studied by thermogravimetric analysis that shows the thermal degradation of rigid and plasticized PVC/PMMA is a process composed of two‐steps and that PMMA exercises a stabilizing effect on the thermal degradation of PVC during the first step by decreasing the rate of dehydrochlorination. J. VINYL ADDIT. TECHNOL., 25:E73–E82, 2019. © 2018 Society of Plastics Engineers     

Miscibility and thermal behavior of poly(vinyl chloride)/feather keratin blends

Various poly(vinyl chloride) (PVC)/feather keratin (FK) blends were prepared via a solution blending method in the presence of N,N‐dimethylformamide as a solvent. The miscibility of the blends was studied with different analytical methods, such as dilute solution viscometry, differential scanning calorimetry, refractometry, and atomic force microscopy. According to the results obtained from these techniques, it was concluded that the PVC/FK blend was miscible in all the studied compositions. Specific interactions between carbonyl groups of the FK structure and hydrogen from the chlorine‐containing carbon of the PVC were found to be responsible for the observed miscibility on the basis of Fourier transform infrared spectroscopy. Furthermore, increasing the FK content in the blends resulted in their miscibility enhancement. The thermal stability of the samples, as an important characteristic of biobased polymer blends, was finally examined in terms of their FK weight percentage and application temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Phase separation of impact‐modified PVC/PMMA blends under melt‐blending conditions

Poly (vinyl chlride)/Poly (methyl methacrylate) (PVC/PMMA) blends were prepared by melt blending at 160°C and 190°C over an entire composition range. The miscibility of the blends was characterized by dynamic mechanical thermal analysis, transmission electron microscopy, and light transmittance testing. The blends prepared at 160°C were homogeneous on our observed scale, while the blends prepared at 190°C clearly showed phase separation. The stress‐strain behaviors of the blends prepared at 160°C were investigated. The results showed that the toughness of the blends could be improved by an increase of PVC content, resulting effectively in a removal of intrinsic strain softening, a decrease in yield stress, and an increase in strain hardening. Furthermore, a core‐shell structured modifier was introduced into the PVC/PMMA blends, and the impact property of the blends was studied. The results showed that the addition of rubber particles could improve the toughness of the two series of blends. However, the blends prepared at 190°C had higher impact strengths than those prepared at 160°C, a result which may be attributed to phase separation. J. VINYL ADDIT. TECHNOL., 19:11–17, 2013. © 2013 Society of Plastics Engineers     

Study on the damping of EVM based blends

The mechanical and damping properties of blends of ethylene‐vinyl acetate rubber(VA content >40 wt %) (EVM)/nitrile butadiene rubber (NBR) and EVM/ethylene‐propylene‐diene copolymer (EPDM), both with 1.4 phr BIPB (bis (tert‐butyl peroxy isopropyl) benzene) as curing agent, were investigated by DMA. The effect of polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and dicumyl peroxide (DCP) on the damping and mechanical properties of both rubber blends were studied. The results showed that in EVM/EPDM/PVC blends, EPDM was immiscible with EVM and could not expand the damping range of EVM at low temperature. PVC was miscible with EVM and dramatically improved the damping property of EVM at high temperature while keeping good mechanical performance. In EVM/NBR/PVC blends, PVC was partially miscible with EVM/NBR blends and remarkably widened the effective damping temperature range from 41.1°C for EVM/NBR to 62.4°C, while CPVC mixed EVM/NBR blends had an expanded effective damping temperature range of 63.5°C with only one damping peak. Curing agents BIPB and DCP had a similar influence on EVM/EPDM blends. DCP, however, dramatically raised the height of tan δ peak of EVM/NBR = 80/20 and expanded its effective damping temperature range to 64.9°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of α-MSt content in α-MSAN copolymer on the miscibility of PVC/α-MSAN blends

A series of α-methylstyrene, styrene and acrylonitrile(α-MSAN) copolymers with different α-methylstyrene (α-MSt) content were synthesized by altering α-MSt and St ratios with emulsion copolymerization method. By melt blending these copolymers with PVC resin and di-isooctyl phthalate (DOP), PVC/α-MSAN and PVC/α-MSAN/DOP blends were prepared. The miscibility and morphology of the blends were investigated by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The miscibility of PVC/α-MSAN blends is substantially improved with the increasing α-MSt content in α-MSAN copolymer containing identical AN content and the blends show homogeneous morphology as the α-MSt content in α-MSAN copolymer is up to 22.5wt%. α-MSAN copolymer containing 37.5wt% α-MSt is fully miscible with PVC throughout the whole composition range. When DOP was introduced into the PVC/α-MSAN blends, a single Tanδ peak over room temperature in DMA detection is found as α-MSt content in α-MSAN copolymer is from 15 to 75 wt%, and morphology result also shows that the PVC and α-MSAN copolymer is miscible under the influence of DOP.     

Effect of intramolecular interactions on the miscibility windows of PVC blends with modified SAN copolymers

We investigated the miscibility windows in the blends of poly(vinyl chloride) (PVC) with chemically modified styrene/acrylonitrile (SAN) copolymers such as α-methyl styrene/acrylonitrile (α SAN), α-methyl styrene/methacrylonitrile (MSMAN). The blends of PVC with α SAN were found to have the broader miscibility window. This enhanced miscibility was interpreted in terms of intramolecular repulsion that originates from unfavorable interaction between counits of the copolymers and also intramolecular association of AN units. The intramolecular interactions were studied by using Fourier transform infrared (FT-IR) spectroscopy. These interactions were reflected by a peak broadening in the nitrile stretching band in the acrylonitrile segments. The intermolecular interactions governing the miscibility in the blends of PVC with the series of copolymers were also discussed.     

PVC／ABS共混体系的相容性与形态结构研究

采用种子乳液聚合技术在聚丁二烯（PB）乳胶粒子上接枝共聚苯乙烯（St）、α-甲基苯乙烯（α—MSt）和丙烯腈（AN）单体,合成了一系列不同AN结合量的ABS和α—MABS接枝共聚物。将其与聚氯乙烯（PVC）树脂熔融共混制得了PVC／AtkS共混物,利用扫描电镜（SEM）、透射电镜（TEM）和动态力学分析仪（DMA）对共混物的相容性和相结构进行了表征。结果发现,在PVC／ABS共混体系中,尽管改变接枝SAN共聚物的AN结合量,PVC和ABS接枝共聚物均为不相容体系;在ABS接枝共聚物中引入α-MSt后,当接枝SAN共聚物的AN结合量为18．7％～23．6％（质量分数）时,共混物在室温以上只存在1个tanδ峰,共混物成为相容体系,当AN结合量达到32．1％（质量分数）时,共混物成为部分相容体系。共混物的相区尺寸明显地依赖于接枝SAN共聚物中的AN结合量,与动态力学性能结果表现出良好的吻合。     

Melt miscibility and mechanical properties of metallocene linear low‐density polyethylene blends with high‐density polyethylene: influence of comonomer type

In this paper, the implications of melt miscibility on the thermal and mechanical properties of linear low‐density polyethylene (LLDPE)/high‐density polyethylene (HDPE) blends were assessed with respect to the influence of the comonomer type. The influence of the latter was examined by selecting one butene LLDPE and one octene LLDPE of very similar weight‐average molecular weight (M_w), molecular‐weight distribution (MWD) and branch content, keeping the comonomer type as the only primary molecular variable. Each of the two metallocene LLDPEs was melt‐blended with the same HDPE at 190 °C in a Haake melt‐blender. The rheological, thermal and mechanical properties were measured by the use of an ARES rheometer, differential scanning calorimeter and Instron machine, respectively. The rheological measurements, made over the linear viscoelastic range, suggested no significant influence of the branch type on the melt miscibility. The rheology results are in agreement with those obtained from previous transmission electron microscopy (TEM) and small‐angle neutron scattering (SANS) studies. The dynamic shear viscosity and total crystallinity of the metallocene (m)‐LLDPE blends with HDPE followed linear additivity. At small strains, the branch type has little or no influence on the melt miscibility and solid‐state properties of the blends. Even the large‐strain mechanical properties, such as tensile strength and elongation at break, were not influenced by the comonomer type. However, the ultimate tensile properties of the HDPE‐rich blends were poor. Incompatibility of the HDPE‐rich blends, as a result of the weak interfaces between the blend components, is suggested to develop at large strains. Copyright © 2005 Society of Chemical Industry     

Plastification of poly(vinyl chloride) by polymer blending

Blends of poly(vinyl chloride) (PVC) with different copolymers have been studied to obtain a plasticized PVC with improved properties and the absence of plasticizer migration. The copolymers used as plasticizers in the blends were acrylonitrile butadiene rubber, ethylene vinyl acetate (EVA), and ethylene-acrylic copolymer (E-Acry). Blends were studied with regard to their processing, miscibility, and mechanical properties, as a function of blend and copolymer composition. The results obtained were compared with those of equivalent compositions in the PVC/dioctyl phthalate (DOP) system. Better results than PVC/DOP were obtained for PVC/acrylonitrile butadiene rubber blends. The plasticizing effect on PVC of EVA and E-Acry copolymers was similar to that of DOP. It is shown that crosslinking PVC/E-Acry blends or increasing the vinyl acetate content in PVC/EVA blends, are alternatives that can increase the compatibility and mechanical properties of these blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1303–1312, 2000     

聚羟基烷酸酯改性聚氯乙烯的研究

通过熔融共混的方法分别制备了聚氯乙烯/邻苯二甲酸二辛酯/聚羟基烷酸酯（PVC/DOP/PHA）和PVC/PHA共混物。研究了PHA逐步代替DOP对共混物力学性能和熔体流动性能的影响规律,利用扫描电子显微镜对所制备的试样进行微观结构分析。结果表明,随着共混体系中PHA用量的增加和DOP的等量减少,与PVC/DOP共混物相比,PVC/DOP/PHA共混物的拉伸强度由21 MPa提高至42 MPa,断裂伸长率先增加而后降低,在PHA含量为10.7 %(质量分数,下同)时出现极大值(350 %);在PVC/PHA体系中,PHA含量增加,PVC/PHA共混物的力学性能及熔体流动速率都显著提高,说明PHA可以作为PVC的一种有效的绿色增塑剂和增韧剂。     

A nonradiative energy transfer fluorescence spectroscopy study of poly(vinyl chloride)/poly(methyl methacrylate) blends

The miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate (PVC/a-PMMA) blends was investigated by nonradiative energy transfer fluorescence spectroscopy using naphthalene-labeled PVC (PVC-N) with anthracene-labeled PMMA (PMMA-A), or anthracene-labeled PVC (PVC-A) with carbazole-labeled PMMA (PMMA-C). The two sets of results indicate an increase in energy transfer efficiency, corresponding to an increase in blend miscibility, as the PVC concentration increases and, more importantly, demonstrate that the same information about blend miscibility can be obtained using different donor-acceptor chromophore pairs and by changing the polymer to which the donor or the acceptor is attached. The effect of the tacticity of PMMA on its miscibility with PVC was also investigated using PMMA-C and PVC-A labeled polymers. The results confirm that PVC/a-PMMA blends are more miscible than PVC/i-PMMA blends over a large range of compositions.     

Mechanical properties of polypropylene blended with esterified and alkylated lignin

Lignin does not show miscibility with commercial polyolefins. Therefore, industrial waste lignin was modified in two different ways and subsequently blended with commercial polypropylene (PP) up to 25 wt %. A Brabender electronic plasticorder was used for melt mixing at 190°C. The influence of different modifications on the mechanical properties and processing stability was studied for both polymer blends. The blends of PP and lignin modified (esterified) with maleic anhydride showed less deterioration in the mechanical properties compared to blends of PP and alkylated lignin with dichloroethane. Intermolecular interactions between the PP matrix and modified lignin were concluded on the basis of indicative values derived from various relevant theoretical models to the experimental data. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

High damping poly (vinyl chloride)/polyurethane blends by tailoring the molecular structure of polycaprolactone-based polyurethanes

Because a blend of limited miscibility level produces high damping characteristics in a composite, copolyurethanes of different molecular structure were synthesized to achieve a desired level of miscibility in PVC. A study of the viscoelastic properties of blends of a 50-to-50 weight ratio of polyurethanes and PVC showed a steady decrease in miscibility on replacement of polyurethanes synthesized from polycaprolactone diols with a molecular weight of 2000, with polyurethanes synthesized by poly(ethylene oxide) diols, up to 80 mol percent, whereupon the polyurethanes became immiscible. The temperature range of damping for a particular polyurethane could be controlled by adjusting the ratio of PVC to the polyurethane. More polyurethane in the blend shifts the damping range toward lower temperature, and vice versa.     

Blends of low density polyethylene/plasticized poly(vinyl chloride): The rheological,morphological, and mechanical characterization

An experimental study was conducted to investigate the rheological, morphological, and mechanical properties of a heterogeneous polymer blend system consisting of low density polyethylene (LDPE) and plasticized poly(vinyl chloride) (PVC). The components were mixed using a single-screw extruder, which was equipped with a special measuring head for the determination of rheological quantities. The morphology of blends was examined by scanning electron microscopy. Die swell was determined by photography. The velocity of ultrasound through the polymer melt was also measured. The dependencies of viscosity, die swell, and ultrasonic velocity on blend composition were qualitatively similar, exhibiting a minimum at about 70 wt % PVC. The morphology of the blend system at this blending ratio was different from morphologies of the other blends. Tensile properties of blends, except elongation at break, were not significantly inferior to those of the LDPE component.     

New method of determining miscibility in binary polymer blends through hydrodynamic interaction: The free volume approach

A new method has been developed to determine the probability of miscibility in binary polymer blends through hydrodynamic interaction. This is achieved by the measurement of the free volume content in blends of carefully selected systems—styrene acrylonitrile (SAN)/poly(methyl methacrylate) (PMMA), PMMA/poly(vinyl chloride) (PVC), and PVC/polystyrene (PS)—with positron annihilation lifetime spectroscopy. The free volume content can predict the miscible/immiscible nature of the blends but provides no information on the extent of miscibility for different compositions of the blends. We have generalized a model used to understand the viscometric behavior of polymer/solvent systems to polymer/polymer systems through the free volume approach. This model provides two important parameters: a geometric factor (γ) and a hydrodynamic interaction parameter (α). γ depends on the molecular architecture, whereas α accounts for the excess friction at the interface between the constituents of the blend, and we propose that α can serve as a precursor to miscibility in a system and indicate which composition produces a high probability of miscibility. The efficacy of this proposition has been checked with measured free volume data for the three blend systems. The SAN/PMMA system produces a maximum α value of ?209 at 20% PMMA; PVC/PMMA produces a maximum α value of ?57 at 10% PMMA. Interestingly, for the PS/PVC system, α is close to zero throughout the entire concentration range. Therefore, we infer that α is perhaps an appropriate parameter for determining the composition‐dependent probability of miscibility in binary blend systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009